Now, Jian Lu and colleagues have designed a solar-driven hybrid system for electricity–water co-production based on passive interfacial cooling (PIC) (Nat. Water 2, 93–100; 2024). The system consists of a combination of water- and electricity-generating modules, with a total of four functional components, listed from top to bottom: an absorber, thermoelectric generator (TEG), heat sink and evaporator. The absorber conveys the solar energy to the TEG, which is responsible for producing electricity; the heat sink transfers the waste heat from the TEG to the trident-shaped (TS) evaporator where clean freshwater is generated. Mass and energy balances are intertwined, offering continuous water replenishment through the straight vertical channels of the evaporator. Interfaces play a key role in this technology, directly affecting the two-module unit performance. The first is between the heat sink and the evaporator, which ensures highly conductive heat transfer from the hot power generator to the cold evaporator unit. Second, there is the evaporator–air interface that affects the water evaporation rate. The evaporative latent heat takes energy from the system itself to sustain the evaporation, therefore cooling down the bottom module in contact with the cold side of the TEG that, in turn, improves the performance of the power generator. This mechanism, encompassed into the PIC region, allows to maintain a very high temperature gradient between the two modules and, therefore, boosts the electricity–water cogeneration efficiency, minimizing, at the same time, the heat losses due to radiation and convection.
The PIC-induced co-generator resulted in a maximum power density of 1.5 W m–2 and an evaporation rate of 2.81 kg m−2 h−1, strikingly outperforming devices without the PIC effect. In particular, the generated power density is shown to be 328% and 88% higher than a coated TEG and a passive cooling cuboid evaporator, respectively. The device results in a stability of 24 h when treating highly concentrated brine solutions and an energy-to-vapor conversion efficiency as high as 91.1%. It is worth noting that the performance strictly depends on the environmental conditions, such as wind speed, relative humidity and sunlight intensity. For example, when the wind speed increases from 0 to 2 m s–1, the resulting power density increases from 1.5 W m–2 to 1.93 W m–2.
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